1. Field of the Invention
The invention relates to the field of power supply monitoring and control. Specifically, the invention relates to tracking and controlling voltage and current supply transitions within specified boundaries from and active or inactive state.
2. Description of Related Art
Many integrated circuits (ICs), such as microprocessors, use a plurality of power supplies of various types and values (e.g., 5.0V, 3.3V, 1.8V) to operate. Power supplies such as regulated linear supplies and switching power supplies may be provided within the integrated circuits supporting circuitry. Additionally, power supplies may be external to the integrated circuits. For example, many power supplies and power supply conditioning circuits (e.g., DC-DC converters, linear regulators) are provided within a bus configuration where the power supplies and conditioning circuits are coupled to a back plane (e.g., "mother-board"). Circuit-card assemblies are then coupled to the bus configuration and are connected to the motherboard to receive power from the external power supplies. Many circuit-cards can then share the same external power supplies.
A rise in the current and voltage levels occurs as a power supply is activated from an off state. Additionally, a fall in the current and voltage levels occurs as a power supply is turned off from an active state. The transitory rise and fall of voltage and current is measured over time and defined as a slew-rate. Different power supplies and conditioning circuits may have different slew rates.
Many integrated circuits require that all of the power supplies and conditioning circuits used to supply the integrated circuit have slew rates within a specific designated range in order for the integrated circuit to operate correctly. Additionally, bus power supply configurations tend to load power supplies differently depending upon the number of circuit-cards attached, and impedance of the bus. Moreover, the variations of the number of circuit-cards on a bus, and bus-circuit impedance, make the slew-rate of the power supplies difficult to control at the inputs to the individual integrated circuits. Therefore, it is advantageous to supply configurable and adaptive voltages and currents in accordance to the requirements of the integrated circuit.